This fixes a low severity bug in a token contract in this repo.
This repo contains code copied from the Soroban example token,
code which recieved a fix in the upstream repo that has not been applied here.
The fix in question, from December, is in this commit:
From reading, I think the main consequence of this bug is that a
previously-unauthorized spender calling transfer_from can write a 0 to the
temporary storage for their own allowance; though it also seems to allow
unintended behavior like allowing authorized spenders to extend the ttl of the
allowance without transfering.
As far as I know this bug does not have a security impact.